Necla Gündüz

Schiff bases and their complexes with metal ions. Part II. Structures of N-n-butyl-2-hydroxy-1-naphthaldimine and bis[N-n-pentyl-2-hydroxy-1-naphthaldiminato]nickel(II)

AbstractThe Schiff base ligand (1), [C15H17NO] crystallizes in the monoclinic space group P21/c witha=10.054(3),b=10.313(3), c=13.173(4)Å, β=107.42(4)°,V=1303.2(7)Å3,Z=4,Dx=1.159 g cm−3, and μ(MoKα)=0.674 cm−1. The C2-O[1.23(1)Å] and C3−C4 [1.33(2)Å] bond lengths are short, due to its quinoidal structure. In the Schiff base nickel complex (2), [Ni(C16H18NO)2] the asymmetric unit is comprised of two half-complexes. It crystallizes in the triclinic space group

THE REACTIONS OF GEMINAL N3P3Ph2Cl4 AND N3P3(NHBut)2Cl4 WITH DIFUNCTIONAL REAGENTS. X-RAY CRYSTALLOGRAPHY, NMR SPECTROSCOPY AND BASICITY OF THE PRODUCTS

P\bar 1

Synthesis, Complex Formation and Spectral Investigation of New Tritopic Bis(Crown Ether) Compounds Containing Recognition Sites for Sodium and Nickel Guest Cations*

witha=5.124(3),b=16.227(3),c=16.886(4)Å, α=95.47(8), β=96.00(1), γ=90.71(4)°,V=1389.6(9) Å3,Z=2,Dx=1.289 g cm−3, and μ(MoKα) =12.1 cm−1. The coordination of the Ni(II) ions are square planar with bond angles between 87.9(1) and 92.1(1)°. The Ni−O and Ni−N distances are 1.819(2), 1.922(2) and 1.823(2), 1.914(3)Å in these two complexes.

X-Ray crystallographic, 1H, and 13C nuclear magnetic resonance investigation of the potentially heptadentate ligand trensal, 2,2',2″-tris(salicylideneimino)triethylamine

Abstract Some of the stable chelate complexes of uranium(VI) were prepared with alkyl or aryl (R) bridged o,o′-dihydroxyaryl Schiff bases of HOC6H4CHNRNCHC6H4OH and HOC10H6CHNRNCHC10H6OH (R: (CH2)n; (C2H4NH)n(C2H4); (C6H4CH2C6H4; o, m, p-C6H4). Their structures were determined by UV, IR and elemental analyses. It is evident that strong ligand-ion interaction usually caused the polymeric structure. This is supported by the high decomposition point and low solubilities of the complexes.

Potentiometric investigations of intramolecular nine- and ten-membered ring hydrogen bonds observed in Schiff bases

Abstract The reactions of geminal N3P3Ph2Cl4 and N3P3(NHBut)2Cl4 with difunctional reagents have been investigated. The N.M.R. spectra of the derivatives are reported. The basicity of these products in nitrobenzene solution is reported and the basicity substituent constants evaluated. X-ray crystallographic data are presented.

Titrations in non-aqueous media. Part VI. Effects of substituents on basicity or acidity of N-salicylidene-2-hydroxyaniline

The basicity of the symmetrical and unsymmetrical tetraphenylporphyrins, namely 5,10,15,20-tetraphenylporphyrin (I) (references), 5-(4-nitrophenyl)-10,15,20-triphenylporphyrin (II), a mixture of 5,10-bis(4-nitrophenyl)-15,20-diphenylporphyrin and 5,15-bis(4-nitrophenyl)-10,20-diphenylporphyrin (III), 5,10,15-tris(4-nitrophenyl)-20-phenylporphyrin (IV), 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (V), 5-(4-aminophenyl)-10,15,20-triphenylporphyrin (VI), a mixture of 5,10-bis(4-aminophenyl)-15,20-diphenylporphyrin and 5,15-bis(4-aminophenyl)-10,20-diphenylporphyrin (VII), 5,10,15-tris(4-aminophenyl)-20-phenylporphyrin (VIII) and 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (IX), was investigated potentiometrically in nitrobenzene solvent. This investigation showed that these compounds are basic rather than acidic. Although they can not be titrated even with tetrabuthylammonium hydroxide, they can easily be titrated with perchloric acid to give well shaped and stoichiometric end-points. In addition they all undergo two proton reactions per porphyrin molecule. However, compounds VI, VII, VIII and IX each shows a second end-point to give three, four, five and six proton reactions, respectively, per porphyrin molecule. Half neutralization potentials (measures of their basicity) of these compounds are: I=368, II=409, III=432, IV=461, V=520, VI=340, VII=302, VIII=238 and IX=225 mV versus Ag/AgCl in methanol. These potentials clearly indicate that, if para-hydrogen with respect to the porphyrin core of tetraphenylporphyrin (I) is replaced with an acidifying nitro group (II, III, IV and V) the basicity of I decreases. This decrease is approximately proportional to the number of nitro groups. Each nitro group decreases the half neutralization potential by about 35 mV. On the other hand, if para-hydrogen indicated above is replaced with a basifying amino group (VI, VII, VIII and IX) the basicity increases. This increase is also approximately proportional to the number of amino groups. Each amino group increases the half neutralization potential by about 36.7 mV. The values 35 and 36.7 mV indicate that in nitrobenzene solvent the electron releasing power of an amino group to the porphyrin system is a little stronger than the electron withdrawing power of a nitro group from the porphyrin system. All these observations reveal that the nitrogen atoms at the core of the porphyrin molecules are strongly influenced by changes at the periphery of the molecules, which is a very good indication that the substituted phenyl groups and the cores of the porphyrins are nearly in the same plane.

Structure and basicity. Part 10. Conductometric and potentiometric titrations of some cyclotriphosphazatrienes in non-aqueous media. The conductivities of alkali-metal acetates on titration with perchloric acid in acetic acid

Abstract New bis(crown ether) ligands (1 - 3) of Schiff base type containing recognition sites for sodium and nickel guest cations have been synthesized by the condensation of two equivalents of 4′-formyl-5′-hydroxy(benzo-15-crown-5)with 1,5-diamino-3-azapentane, 1,8-diamino-3,6- diazaoctane or 1,8-diamino-3,6-dioxaoctane. Homonuclear ditopic crystalline 2:1 (Na+:ligand) complexes (1a - 3a) of the ligands with NaClO4 have been prepared. Heteronuclear tritopic crystalline 2:1:1 (Na⊕ : Ni2⊕ : ligand) complexes (2b and 3b) have also been synthesized from the reactions of the ditopic complexes (2a and 3a) with Ni(CH3COO)2 · 6H2O. The UV-VIS spectra of 1 - 3, their sodium complexes 1a - 3a and sodium-nickel complexes 2b and 3b have been recorded in polar and non-polar solvents as well as in acidic and basic media. In polar solvents and basic solutions, tautomeric equilibria (phenol-imine and keto-amine forms, O-H···N⇌O···H-N ) are present, depending on the hydrogen bonding. The results indicate that the concentrations of the keto forms of the compounds generally increase as the polarity of the solvent increases

Titrations in non-aqueous media. Part XI. Basicities of open-chain and cyclic polyether derivatives of aniline

The potentially heptadentate ligand trensal, 2.2′2″-tris(salicylideneimino)triethylamine, has been investigated by n.m.r. spectroscopy and X-ray crystallography. The 1H and 13C n.m.r. spectra of this compound have been completely assigned. The single crystal X-ray investigation, R=0.073, showed the compound to be monoclinic, space group P21/c, a=9.857(2), b=11.208(2), c= 22.910(4)A, β=98.81(1)°. Strong intramolecular hydrogen bonding occurs between the hydroxy hydrogen atoms and the azomethine nitrogen atoms. The compound exhibits an approximate three-fold axis when looking down the unique nitrogen atom through the plane C(11)–C(21)–C(31).